Sainsbury's isn't the only supermarket to pay heed to consumer trends and concentrate its efforts on sourcing more produce from Northern Ireland.

Main rival Tesco said it now buys £580m worth of food and drink from producers and processors on these shores, a jump of 16% on 2012 and more than double the amount Sainsburys buys.

However, in terms of store presence, with just 13, Sainsburys is dwarfed by Tesco's presence which includes around 51 locations.

Tesco said it buys 1,200 product lines from over 90 suppliers here under its Taste Northern Ireland logo with Punjana in Belfast making Tesco Finest range tea bags, milk supplied by Dale Farm, 55 million eggs a year from Skea, chicken from Moy Park and Tesco Finest range sausages from Finnebrogue in Downpatrick.

Asda didn't put a figure on the value of produce from Northern Ireland it buys but said it sources from 100 food companies here supplying 1,350 product lines.

That works out at 20% of its total food sold on these shores, or £1 for every £5 spent in its 17 stores. Lidl said 30% of its turnover in Northern Ireland is generated from locally-sourced produce.

"Lidl NI works with over 35 Northern Irish suppliers and are continuing to grow this number," it said in a statement. "Today we source fresh meat, fresh chicken, milk, eggs, bread, fruit, vegetables, plants, flowers and many other speciality products locally.

Marks & Spencer wouldn't comment on the value of produce it sources in Northern Ireland but said it buys local beef and pork products, chicken and turkey products, venison, potatoes, bread, eggs, dairy produce including milk, butter and cheese, salads and coleslaws and carrots.

Fair play in supply chain essential

Ulster Farmers' Union President Harry Sinclair welcomes the emphasis supermarkets have put on buying produce from Northern Ireland, but warned they need to make sure suppliers remain profitable...

"It is great to see products from Northern Ireland making their way on to supermarket shelves; this is recognition of the top quality and world class agri-food industry we have here. While this is good news and should be celebrated, the food supply chain is notoriously dysfunctional and the UFU wants to be sure that supermarkets are treating suppliers and primary producers fairly. The contribution of farmers to this cornerstone industry cannot be overlooked. It is in the interests of everyone, including supermarkets, that all partners, including primary producers, in the supply chain are profitable. The recent instatement of the Groceries Code Adjudicator should help to ensure 'fair play' in the supply chain and to address the power imbalance that exists between retailers and suppliers."